I was on The Tweenies - fans will be stunned at what's in the costumes

The Tweenies was a beloved noughties kids' show that gripped the nation's children with its brightly coloured, puppet-like characters and quirky storylines.

The CBBC show, which aired from 1999 to 2002, was so popular that 80 percent of British children aged two to six watched it.

The Tweenies was set in a preschool and followed the adventures of four characters, Milo, Jake, Bella, and Fizz, along with their friends Max and Judy and their dog Doodles.

But after more than two decades off-air, character star Bob Golding, who played Milo and Max, has revealed a shocking set secret that no doubt will leave fans stunned.

Bob confessed to The Sun that he and fellow character stars Sally Preisig, Emma Weaver, Colleen Daley, and Sinead Rushe were never actually inside the legendary costumes.

Instead, they were just the voice-over actors.

Underneath the colourful, thick foamed suits were a carefully-selected range of 'skin actors'.

He told the publication: 'The skin actors would go in first to rehearse with the director what the scene content would be.

'They were all five foot or under and very fit and obviously strong because the strain on your neck with those heads was huge.

'So they would go in and rehearse that without all the costumes on and just move around like actors.'

He revealed they would learn the songs and dances with musical directors Graham Pike and Liz Kitchen, before watching the skin actors play out the scenes a week later.

The skin actors would then perform for the shooting while they voiced over the top.

Bob also revealed a unique system which created a more expressive and animated look to the costumes.

Inside the heavy suits was a secret mechanism called the Performance Animatronic Control System.

It consisted of foot pedals and small wheels at the ends of the gloves that could be tweaked. To move the jaw, there was a sensor inside the thumb.

Bob revealed the system took months for the actors to perfect.

The tweenies featured Bella, Milo, Fizz, and Jake.

Bella, who was coloured purple, was typically the confident and leading character of the group and was usually involved in more mischievous storylines.

Milo, whose suit was red, spent his days burning energy and boosting up his fellow pals.

Fizz, who was coloured yellow, was a sweet yet sometimes vain individual who loved to sing and dance ballet.

And the youngster of the group was Jake, who was blue in colour, and typically the most curious and relaxed.

The group, along with their dogs Doodles and Izzles, spent their days in their bright playroom which featured an outdoor play area.

They were cared for and guided by caretakers Max and Judy - whose full faces were never seen.

The show's iconic theme song featured the refrain: 'Hey, hey, are you ready to play?'